After the fabrication of semiconductor dies, a packaging process is required to provide the dies support and to protect them against the moisture corrosion or any other damage. A conventional semiconductor dies packaging process includes die bonding, then wire bonding, and finally used molding compound to seal the package, so that the circuits on the dies can be protected against the moisture corrosion. For high frequency devices, however, the conventional packaging method may suppress high frequency performance of the devices. In the air cavity packaging method, a sealed cavity is formed around the dies in the package. The medium in the package is gas (e.g., vacuum, nitrogen, air), which can provide good insulation and the power consumption can thus be reduced. The air cavity packaging method is especially applicable to high frequency and high power devices such as RF system, microwave system, MEMS, MOEMS and photo-sensing devices (e.g., CCD, CMOS).
In the conventional air cavity packaging, however, while curing the adhesive agent by heating, voids occur frequently in the adhesive agent owing to the air in the air cavity exhausting to the outside. If plural connected packages are produced at once, the adhesive agent will overflow to the adjacent packages due to the release of the air pressure from the air cavities, which leads to degradation of the performance of the dies. Therefore, in the conventional air cavity packaging, usually only one package is produced at one time to prevent the problem of voids and adhesive agent overflow, which limits the yield of packages.